(CNN) - As he stood on the floating Apollo 11 capsule, Navy SEAL John Wolfram was very aware that the safety of the first men to walk on the moon was in his hands. The whole world was watching.

Amazing circumstances - for a guy just two years out of high school.

It was July 24, 1969 - four days after the historic landing - and millions were anxious to know whether the astronauts had survived their fiery fall into the Pacific about a thousand miles off Hawaii. Minutes before he stepped onto the tiny capsule, it had been plummeting from space into the atmosphere at thousands of miles per hour. Parts of the spacecraft's shell were blackened. Wolfram could see steam still rising from it.

"I looked in the hatch window to see if the astronauts were OK," recalls Wolfram. "They smiled and gave me a thumbs up. Being the first to look them in the eye and see that they're OK - it's quite a rush."

On this 43rd anniversary of the well-known mission, here's an Apollo 11 story that's told less often.

It's the story of a handpicked four-man team of tough Navy SEALs who played a key role in what may be mankind's greatest technological achievement.

Cell phones, Internet, satellite television - they’re all technologies our society takes for granted. But about half a century ago, those types of communications were pure science fiction. Telstar, the world’s first global communications satellite, set us on a path to change that, and on Thursday the National Air and Space Museum marked the 50th anniversary of Telstar’s first television transmission.

Telstar’s July 1962 launch marked the birth of telecommunications, sending the first global transmission of a television signal. That first picture came from Andover Earth Station, Maine, to the Pleumeur-Bodou Telecom Center, Brittany, France. The satellite also handled telephone and fax signals.

Some of the first public video from the satellite included remarks from then-President John F. Kennedy, and a baseball game between the Philadelphia Phillies and Chicago Cubs.

There we were on Saturday night, just the two of us. John Glenn, who 50 years ago today became the first American to sit alone atop a 125-ton rocket and shoot around the world three times at more than 17,000 miles an hour.

Glenn's mission made him a national hero who eventually left NASA and later served four terms as a U.S. senator from Ohio.

But he couldn't stay away. Fourteen years ago, at age 77, he returned to orbit - on a much heralded shuttle mission aboard Discovery that put him in the history books again as the oldest person to travel to space.

Now, at 90, Glenn is still lean and fit.

Would he go again? “I’d go tomorrow if I could,” he said.

Of course, the shuttle program is over, which Glenn told me he’s not happy about.

I asked Glenn what was going through his head while he sat in that Mercury capsule waiting to lift off. It seemed like the whole world was talking about the race with Moscow to dominate space and rising Cold War tensions.

No, he said. He didn't feel any pressure from the space race or the Cold War. The Soviet Union had already orbited a man around the world, Glenn told me.

He was absorbed in the task at hand.

“You just wanted to do the best job you could do,” he said.

There was no time then to think about the bigger picture.

Everything was a “change of status,” Glenn said. “Check the pressures. Change of status. It lights and you’re going, 'Change of status. Do I have orbital speed? Change of status.' ”

'Godspeed, John Glenn': 'I didn't hear it'

Gaining orbital speed was a big deal. Scott Carpenter knew it.

Carpenter - who was Glenn’s back-up for the flight - sat in Mission Control on that day 50 years ago. Three months later, Carpenter would become the second American to orbit the Earth.

In fact, it was Carpenter who uttered those famous words as Glenn lifted off: “Godspeed, John Glenn.”

I asked Carpenter, who was now sitting just a few feet away from where Glenn and I had been chatting, if he'd thought about those words beforehand.

“I never thought about it,” Carpenter told me. “What John needed that no American had before was speed." The previous Mercury flights - piloted by Alan Shepard and Gus Grissom - had been suborbital. They didn’t need the velocity Glenn needed to make it to orbit.

What I didn’t know was that Glenn was on a different communications channel when Carpenter said those historic words.

But 36 years later aboard Discovery, Carpenter was back in Mission Control and said it again, “Godspeed, John Glenn.” That time Glenn says he heard it in real time.

Astronaut/aquanaut

Carpenter, a Navy man, has a love for outer space and inner space.

When he left NASA, he explored underwater adventures as an aquanaut in the Navy’s Man in the Sea Project - at one point living and working on the ocean floor for 30 days straight. Later Carpenter served as director of the Navy’s Aquanaut Operations.

“I still can’t make up my mind whether I like outer or inner space better,” he said - adding with a smile, “But there’s a difference in glory.”

Editor's note: CNN contributor Bob Greene is a best-selling author whose books include "Late Edition: A Love Story" and "Once Upon a Town: The Miracle of the North Platte Canteen."

For half a century, the world has applauded John Glenn as a heart-stirring American hero. He lifted the nation's spirits when, as one of the original Mercury 7 astronauts, he was blasted alone into orbit around the Earth; the enduring affection for him is so powerful that even now people find themselves misting up at the sight of his face or the sound of his voice.

But for all these years, Glenn has had a hero of his own, someone who he has seen display endless courage of a different kind.

On Monday, it will be exactly 50 years since the day John Glenn helped America turn the corner in the Space Race with the Soviets.

When Glenn became the first American to orbit the planet, it triggered a celebration and sense of pride that arguably was crucial to astronauts later setting foot on the moon.

So huge was this national mood swing that followers of CNN's Light Years space and science blog still remember it a half-century later. They're sharing their memories about where they were and what they felt on February 20, 1962.

"I was a junior in high school when John Glenn went on his ride around the Earth," wrote OldGoat in Light Years comments. "It seemed amazing at the time that such a thing could be done."

It's easy to forget that not long before Glenn's three-orbit flight, the public knew NASA more "for its failures and delays than for its space exploration," wrote Tom Streissguth in his Glenn biography. "The Soviet space program was far more successful."

More than ten months before Glenn's flight, Moscow fired the first shot in this battle to dominate human space exploration, when cosmonaut Yuri Gagarin became the first man to orbit the Earth.

After Washington recovered from the shock, it answered with Alan Shepard and Gus Grissom - America's first and second men in space. But their 15-minute missions blasted off and then splashed down. No orbiting. They paled in comparison to Gagarin's single-orbit around-the-world ride.

Then Moscow embarrassed Washington again when Gherman Titov circled the planet - not once - but 16 times.

It sure looked like America might be on its way to losing the Space Race.

"Everything about the space program was cool back then and really gave the U.S. something to shoot for," said Light Years follower Bob Knippel. "It's not at all like that today, the way it permeated American consciousness."

Leading up to Glenn's mission, there were safety questions about his 125-ton Atlas rocket. Streissguth wrote that during one testing period the rocket "failed four out of every 10 launches."

"People have always asked if I was afraid," Glenn wrote in his 2000 memoir. "I wasn't. Constructive apprehension is more like it."

After many delays, the launch went without a hitch. But during re-entry a false alarm prompted worries about the spacecraft's protective heat shield. Light Years follower Montello recalled CBS news anchor "Walter Cronkite's nonstop commentary during the time Glenn was in space and the elation when he landed safely."

As Light Years commenter The_Mick, put it: "John Glenn's flight put us in the major leagues!" While Judie wrote, "I remember it well and was so proud; I still am!"

In fact, the national celebration for Glenn's mission was so intense Washington held a parade for the 40-year-old Marine Corps colonel.

Thousands cheered as he left a White House meeting with President Kennedy and was driven down Pennsylvania Avenue to Capitol Hill. There, Glenn addressed Congress saying, "I believe we're on the brink of an era of expansion of knowledge about ourselves and our surroundings that is beyond comprehension." You can see Glenn's handwritten speech notes here.

The emotional momentum spurred by Glenn's successful flight culminated just seven years later, when Apollo 11's Neil Armstrong, Buzz Aldrin, Michael Collins and their colleagues accomplished a lunar landing that many said was impossible.

Now, a half-century after Glenn's flight, Light Years follower Gregory L. Faith told us he still has "a picture of Mr. Glenn in his U.S. Marine Corps uniform with his signature. It is my only prized possession of an era gone by."

Works4me summed up feelings for Glenn in three words.

"My first hero."

Our friends at Time and LIFE offer a glimpse of rare and unpublished images of Glenn by some of LIFE's finest photographers.

These images - some in the gallery above and others at LIFE's website - document a brief period, and some would say perhaps a more naive, less-cynical time, when Glenn and his astronaut colleagues inspired the nation.

What about now?

Who's inspiring the next generation?

And if not space, in what new competitive arenas will they test themselves? Stay tuned.

NASA is celebrating the 50th anniversary of the first American in orbit.

Back in 1959, NASA selected John Glenn as one of the original group of seven astronauts for the Mercury program.

Three years later, he blasted off to the famous words, "Godspeed John Glenn," becoming the first American to orbit the Earth. To honor this landmark, we’re taking a look back at Glenn’s historic flights into space.

First American to circle the Earth

On February 20, 1962, Glenn made his famous journey around the planet aboard NASA's Friendship 7 spacecraft. During the nearly five-hour mission, he circled the globe three times. The mission wasn't perfect. A trouble indicator light warned that a clamp holding the spacecraft's heat shield had been released too early. Mission controllers feared that the heat shield was loose. The shield was meant to protect Glenn's spacecraft from burning up during re-entry. As a safety measure, a "retropack" that would normally have been jettisoned was allowed to stay on the spacecraft to hold the heat shield. It turned out that warning light was a false alarm. Glenn splashed down safely to much fanfare at home. Watch the incredible archival footage of this historic trip.

Glenn made headlines again in 1998 when he rejoined NASA at age 77 to become the oldest person ever to go into space. Glenn’s trip aboard the shuttle Discovery helped NASA learn about the effects of space flight on older people. Watch him quip about breaking a hip in space.

Friday, at age 90, Glenn joined fellow “Mercury Seven” astronaut Scott Carpenter to reminisce about their adventures and reflect on the U.S. space program. Appropriately, it was Carpenter who announced those famous words a half century ago: "Godspeed John Glenn." Learn just how dangerous their missions were and what types of concerns that scientists had about Glenn’s health.

On December 21, 1968, Apollo 8 launched for the Moon. Apollo 8 was crewed by commander Frank Borman, command module pilot James Lovell (who would also fly aboard Apollo 13), and lunar module pilot William Anders. They were the first humans to leave low-Earth orbit and see the dark side of the Moon.

The crew of Apollo 8 were also the first humans to look upon Earth as a whole planet. The crew took the famous Earthrise photo, seen above, on December 24.

The successful completion of Apollo 8 was an important milestone in the journey to land on the Moon.
More on Apollo 8.

Mariner 2 was the first planetary spacecraft to fly, acting as a backup to Mariner 1, which failed shortly after launch. By the time Mariner 2 approached Venus, it had lost a solar panel and possibly collided with a small object.

At its closest, Mariner 2 was 34,773 km from Venus.

The spacecraft carried science instruments that discovered Venus' hot surface temperatures and high surface pressure. Mariner 2 also revealed that Venus has an atmosphere made up mostly of carbon dioxide and perpetual cloud cover.

Mariner 2 also helped determine that solar winds are continuously streaming in the space between the planets.

On December 8, 2010, SpaceX successfully completed a demonstration flight for NASA's Commercial Orbital Transportation Services (COTS) program with the flight of the first Falcon9 carrying a Dragon capsule.

The Dragon capsule completed two orbits and splashed down safely in the Pacific Ocean, making SpaceX the first commercial company to successfully launch and retrieve a capsule from low-Earth orbit.

SpaceX later revealed that Dragon carried a secret payload: a wheel of cheese.

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